Answer:
It took him 13.8 sec to run
Step-by-step explanation:
Time to spin 6 times can be represented mathematically by "6 s". Then the total time it took him to get to the tree (which must be the addition of the time spinning plus the time running) is:
6 s + r = 21 sec
since each spin takes him 1.2 sec, then we have:
6 (1.2 sec) + r = 21 sec
7.2 sec + r = 21 sec
r = 21 sec - 7.2 sec
r = 13.8 sec